Hydraulic aluminum ingot positioner and pusher

ABSTRACT

An ingot upender and pusher.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 60/601,727, filed Aug. 16, 2004, incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus for upending aluminum ingots to stack them on their side and push the horizontally stacked ingots into and through a furnace.

Prior equipment used to push aluminum ingots weighing up to 35,000 pounds was fraught with problems and was subject to failures, resulting in downtime on the production line. For example, shoes which carry the ingot into the furnace would skew as the ingot was indexed through the furnace, becoming stuck to the ingot, resulting in costly downtime to correct the problem.

It will be appreciated that considerable force is required to push horizontally stacked ingots totaling 1 MM pounds through the furnace. Thus, severe demands are made on equipment. Prior equipment relied on foundation components for rigidity, alignment and stability, which was problematic. Further, prior equipment had frictional problems as the ingots were indexed through the furnace, requiring higher hydraulic pressures and forces, resulting in premature wear on equipment. In addition, the ingots would often get skewed in the furnace, resulting in production downtime and maintenance delays for repair, as stated previously.

In the prior references, U.S. Pat. Nos. 4,859,178 and 4,938,690 disclose an ingot pusher furnace which includes means for reducing heat loss from the charging and discharging ends of the furnace so as to produce more efficient and uniform heating of the ingots. The pusher furnace includes support rails which extend between a first opening in the front wall and a second opening in the rear wall and terminates inside of the charging and discharging doors. The charging and discharging doors extend below the support rails in their closed position so as to provide a positive seal.

U.S. Pat. No. 4,941,823 discloses an ingot pusher furnace of the vertical air flow type which includes adjustable side baffles hingedly connected to lower ends of respective vertical side baffles to prevent the “short circuiting” of heated gases around the ends of an ingot to be heated. The adjustable side baffles are movable from a vertical position to an angled position so that its upper ends are in closely spaced proximity with the outer faces on the end portions of the shorter length ingot so as to produce a more uniform and faster heat transfer along the entire length thereof.

U.S. Pat. No. 5,301,929 discloses a crosshead shoe for the sliding transport on rails of a material to be annealed having, for the lateral guiding on the rails, an approximately U-shaped cross section with downwardly projecting legs. Special glide elements are provided on the side of the glide shoe which faces the glide plane, and/or the rail, which glide elements are designed so that as little wear and friction as possible occur during the movement of the crosshead shoes. The glide elements have glide surfaces for this purpose, the side surfaces of which glide surfaces are rounded and/or downwardly inclined, and/or the peripheral edges of which are associated with one another in obtuse angles or have a shape which is at least partially circular.

In spite of these disclosures, there is still a great need for an ingot positioner and upender apparatus that can operate to push ingot through a furnace without differential frictional events affecting ingot straightness, thus eliminating possibility of skewing. The present invention provides such an apparatus for upending aluminum ingot, moving or indexing the ingots through a furnace without skewing, and being self-protecting to alleviate catastrophic damage in case of any single component failure.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method and apparatus for upending aluminum ingots on their side and indexing the ingots through a tunnel furnace.

It is another object of the invention to provide an apparatus having twin hydraulic cylinders for upending aluminum ingots.

It is still another object of the invention to provide an apparatus for upending and indexing aluminum ingot through a tunnel furnace having excellent equipment reliability while requiring only minimal maintenance.

It is still another object of the invention to provide an apparatus for upending and indexing aluminum ingot through a tunnel furnace that is self-protecting to alleviate catastrophic damage in case of any single component failure.

In accordance with these objects, there is provided a method of upending and indexing rectangular-shaped aluminum ingots on their side through a tunnel furnace, the method comprising the steps of providing an aluminum rectangular-shaped ingot having two large flat surfaces and two relatively small sides, the ingot being provided with the flat surfaces substantially parallel to ground surfaces. An apparatus is provided for upending the ingot onto one of its sides, the apparatus comprising an ingot support frame comprising spaced-apart ingot support members fastened to an axle mounted on a mainframe, the axle being rotatable to transfer the ingot from a horizontal to a vertical position to rest on ingot support shoes. The axle has an arm fastened thereto, the arm being activated by a first hydraulic means to rotate the ingot support frame. A main frame is provided having the ingot support shoes for carrying the ingot on one of its small sides to the tunnel furnace, with the shoes traveling on rails passing through the furnace. A second hydraulic means is provided in communication with the support shoes to move the ingots into the furnace, thereby horizontally stacking the ingots in the furnace and indexing ingots through the furnace without skewing. The method includes placing the flat side of the ingot on the ingot support members, activating the first hydraulic means to position the ingot on its small side on the ingot shoes, and activating the second hydraulic means to move the shoes carrying the ingot into the tunnel furnace while indexing the ingots through the furnace.

The invention also includes an apparatus for upending and indexing rectangular-shaped ingot horizontally stacked on their side through a tunnel furnace, the ingot having two large flat surfaces and two relatively small sides. The apparatus is comprised of an ingot support frame for receiving an ingot on one of its large flat surface. The support frame has spaced-apart ingot support members fastened to an axle and bearings and bearing supports mounted on a main frame for carrying the axle, the ingot support frame rotatable to transfer the ingot to vertical position thereby having a small side of the ingot resting on ingot support shoes. An arm member is provided having one end fastened to the axle and a second end fastened to a first hydraulic means, the first hydraulic means activated to rotate the ingot support frame thereby transferring the ingot to the vertical position. A main frame is provided incorporating the ingot support shoes for carrying the ingot on one of the small sides to the tunnel furnace, the shoes mounted rails entering the furnace. A second hydraulic means is provided in communication with the support shoes, the second hydraulic means adapted to move the ingot into the furnace.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates steps for casting ingots and moving them through a furnace using the invention.

FIG. 2 is an isometric view of the ingot positioner and pusher.

FIG. 3 is another isometric view of the ingot positioner and pusher.

FIG. 4A is a top view of the apparatus.

FIG. 4B is a view showing controls for the hydraulic cylinders.

FIG. 5 is an end view of the apparatus.

FIG. 6 is a side view of the apparatus illustrating an ingot in outline in the home position and the ingot shown in outline form upended for indexing into a tunnel furnace.

FIG. 7 is a side view along section line B-B of FIG. 4A showing the rack and pinion gears arrangement.

FIG. 8 is an end view showing the rack and pinion apparatus along the section line A-A of FIG. 7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is illustrated a flow schematic of aluminum metal processing from casting molten metal into ingots to hot line rolling of ingot. In the process, it will be noted that “ingots” 2 are melted in a furnace 4 where the chemistry is adjusted before being cast into ingots 6 having the desired shape and chemistry suitable for rolling. Ingots 6 are scalped at scalper 8 to remove an oxide layer and ensure that the top and bottom of the ingot are parallel. It will be noted that scalped ingots 6 leaving scalper 8 are processed in the horizontal position. In accordance with the invention, scalped ingots 6 are required to be upended and moved through ingot heating furnace 10 utilizing an ingot upender and pusher apparatus 12. Ingots 6 are upended and indexed through the furnace to maximize furnace loading and to ensure uniformity of heat treating. Further, to insure production efficiency and uptime, it is imperative that the ingots are moved through the furnace without fear of equipment breakdowns common with prior equipment.

After heating in furnace 10, the ingots are hot rolled at rolling stand 14 where they are rolled into sheet and wound into coils. The coils may be further processed by cold rolling, annealing and coating, for example.

In FIG. 2, there is shown a perspective view of ingot upender and pusher apparatus 12. In this view, ingot upender and pusher apparatus 12 are shown with an ingot 6 carried by arms 18 prior to the ingot being upended for placing it on ingot side 20 which is positioned on sliding shoes 22 for purposes of moving or pushing the ingot into furnace 10, as shown in FIG. 1, for example. In FIG. 2, it will be noted that arms 18 are supported by axle 24 which is carried by journal bearings 26. For purposes of upending ingot 6 onto side 20, arms 28 are fastened to axle 24. Arms 28, in turn, are attached to sliding member 30 of hydraulic cylinder 32 (see FIG. 3). That is, in operation an ingot 6 is placed on arms 18, hydraulic cylinders 32 are activated to retract member 30. This, in turn, rotates arms 28 and thereby lowers ingot 6 onto side 20 where it is supported by shoes 22 ready for introduction into furnace 10. Shoes 22 are pushed by pusher trolley cars 50 and slide on frame mounted wear plates 23 (FIG. 4A). Pusher trolley cars ride on sealed and lubricated runner wheels which run on frame wear plates 61 (FIG. 8).

From FIGS. 2 and 3, it will be seen that journal bearings 26 are supported by support members 34 which are located on floor 36. From FIG. 4A, it will be noted that hydraulic cylinders 32 are used on each end of axle 24.

After ingot 6 is upended to be supported by shoes 22 on side 20, the shoes, and therefore ingot, are pushed forward by hydraulic cylinders 40 and 42 (FIG. 3). It will be understood that these cylinders advance trolley cars 50 (FIG. 4A) which contact shoes 22 and push them toward the entrance of furnace 10. Ingots 6 already existing in furnace 10 (see FIG. 1) are pushed farther through furnace 10 by the action of hydraulic cylinders 40 and 42. Thus, when the furnace is full, as one ingot is added, another one is pushed near the exit furnace door where an exit unloading apparatus withdraws ingot 6 from the furnace while still resting on shoes 22 and transports ingot to rolling tables for rolling (see FIG. 1). The shoes are indexed back to the entry end of furnace to be reused.

It should be understood that aluminum ingots processed by this invention can weigh up to 35,000 pounds. Thus, the pusher apparatus can be required to push up to 1 MM pounds of ingot in a single operation as it moves a maximum number of ingots through the furnace. Ingots 6, while being supported on shoes 22, slide on iron rails through the furnace. Subsequent sets of shoes 22 with ingot 6 readied for insertion into furnace come in contact with the last set of shoes 22 already inside the furnace supporting previous ingot 6. As cylinders 40 and 42 continue to push subsequent sets of shoes into the furnace, interface contact with the last set of shoes result in those shoes supporting ingot 6, also being indexed or pushed farther into the furnace. This process is repeated until furnace is full of ingot 6 and pre-heating can begin. Accordingly, the horizontally stacked ingots must be slidingly transported through furnace 10 without fear of skewing inside the furnace. Since frictional differences will always exist between each one of shoes 22 and rail 23 they are in contact with, and frictional differences will result in different forces required by each cylinder to move ingot 6 on shoes 22, cylinders are hydraulically, mechanically, and electrically linked together such that both cylinders 40 and 42 extend at the same rate on the entrance ingot as it is pushed into the furnace. Referring to FIG. 4A, it will be seen that hydraulic cylinders 40 and 42 have hydraulic fluid feed lines 44, 46, 63 and 64. It will be seen that hydraulic feed lines 44 and 46 supply a constant flow of hydraulic fluid to each cylinder 40 and 42 to retract cylinders to home position. It will also be seen that hydraulic feed lines 63 and 64 supply a constant flow of hydraulic fluid to each cylinder 40 and 42 to extend cylinders to apply force to trolley cars 50, thus in effect applying force to shoes 22 and causing ingot 6, while being supported on shoes 22, to slide into the furnace. It is important that both cylinders extend at the same rate, regardless of frictional and force differences to avoid skewing and binding of shoes as they move the ingot towards and through the furnace, avoiding undue wear on equipment and the phenomenon of shoes sticking to side 20 of ingot 6. This phenomenon has been shown to exist when ingots are skewed as they pass through the furnace due to rotational movement at the shoe/ingot interface (FIG. 4A) coupled with plastic properties of aluminum at higher temperatures.

In this invention, shoes 22 carry ingot 6 all the way through the furnace. As heated ingot is removed from the exit end of the furnace, the shoes are recycled to the entry end of the furnace and reused via an overhead trolley/grab assembly.

The pusher assembly incorporates rack 52 and pinion gears 54, as shown in FIG. 2. Both pusher trolley cars 50 from hydraulic cylinders 40 and 42 used to push shoes 22 are fastened together using pinions 54 (FIG. 5). Referring further to FIG. 5, it should be noted that pinion gears 54 are joined together by a shaft 56. Shaft 56 extends through the pinion gear and is mounted in journal bearings 58 (see FIGS. 2 and 5) where it is free to rotate. Journal bearings 58 are fixedly fastened to pusher trolley cars 50 which are used to push shoes 22 and ingot 6 through the furnace. As hydraulic flow is applied to hydraulic cylinders 40 and/or 42 and hydraulic force develops and is applied to pusher trolley cars 50 and shoes 22 move towards the furnace, pinion gears 54 traverse within rack 52 (FIG. 2). Thus, even if there is a failure in one of hydraulic cylinders 40 or 42, or a failure in one of either control valves for hydraulic cylinders 40 or 42 or appreciable frictional differences between shoes 22, pusher trolley cars 50 will still traverse at the same rate. Differential forces due to any of aforementioned anomalies will be distributed through the rack and pinion arrangement, thereby avoiding skewing of ingot 6 in the furnace.

FIG. 5 is an end view showing location of hydraulic cylinders 40 and 42 used to push shoes 22. Hydraulic cylinders 32 are shown attached to arms 28 which, in turn, are fastened to axle 24. In this view, axle 24 is shown attached to arms 18 used for carrying and upending ingot 6 onto shoes 22. It will be seen that axle 24 is carried on journal bearings 26. Also, pinion gears 54 are shown connected by shaft 56 which is carried by journal bearings 58.

FIG. 6 is a side view of the apparatus showing ingot 6 in the horizontal position resting on member 18. Member 18 and ingot 6 are also shown in outline form after the ingot has been upended onto its small side 20 to rest on shoes 22. The ingot is then pushed towards the furnace and arms or members 18 are returned to the home position to receive another ingot to be upended.

Referring now to FIG. 7, there is shown a side view along section line B-B of FIG. 4 showing pusher trolley car wheels 62 and wear plates 61, allowing pusher trolley car 50 to advance with minimal frictional involvement and contact shoes 22 which then carry ingot into furnace 10. It will be seen that support frame 34 is anchored by fasteners 60 in floor 36 and support frame 34 carries wheels 62. Also, arm member 18 is shown in the upended position. Pinion gears 54 are shown engaging racks 52 at a position withdrawn from furnace 10. Thus, when ingot 6 is placed on shoes 22, hydraulic cylinders operate to push the ingot into furnace 10 using arm 51 by applying hydraulic force to pusher trolley car 50 which push on shoes 22.

It will be seen from FIG. 8, which is a cross-sectional view along section line A-A of FIG. 7, that pinion gears 54 are joined by axle 56 which is mounted in journals 58. Journal bearings 58, in turn, are mounted on members 50. Thus, as hydraulic force is applied to members 50 and shoes 22 move towards the furnace, pinion gears 54 traverse within racks 52 and because gears 54 are joined via axle 56, even if there is a failure in one of the hydraulic cylinders 40 or 42, or a failure of either control valves for hydraulic cylinders 40 or 42, or appreciable frictional differences between shoes 22, pusher trolley cars 50 will still traverse at the same rate. Differential forces due to any of the aforementioned anomalies will be distributed through the rack and pinion arrangement, thereby avoiding skewing of ingot 6 in the furnace.

An electrical position feedback device is incorporated into each cylinder 40 and 42. This device continually monitors any mismatch of pusher trolley cars position, and if variance becomes beyond an acceptable limit, the system will fault out and technical intervention will be required. Thus, all three modes of safety (parallel hydraulic supply, mechanical rack and pinion, and electrical position feedback) are incorporated into the pusher equipment.

Referring to FIG. 4B, it will be noted that hydraulic pumps 70 and 72 supply fluid to respective directional valves. There are four pumps, two of which have a capacity of 20 GPM and two at 60 GPM. The two 20 GPM pump units are loaded for slow approach speed and the two 60 GPM pumps along with 20 GPM pumps are loaded for fast speed. The electrical signals come from programmable logic controller (PLC) output module 74. Thus a total of 160 GPM is available for maximum push speed. Slow speed is only used during the approach to the ingot shoe period, which is approximately the first two inches of pusher cylinder travel to prevent toppling of the ingot from the shoe.

Directional valves are energized to extend pusher cylinders (40 and 42) via direct output from PLC 74. Flow from each directional valve merges into a single supply piping until splitting back apart near pusher cylinder connection points (lines 63 and 64) thus balancing flow to each pusher cylinder. Return flow from pusher cylinders is via hydraulic piping (lines 44 and 46) and flows back through directional valve to the reservoir (not shown). This path is also balanced via merged piping.

Since flow is directly related to pressure drop, balanced flow will only maintain a balance if pressures remains the same in each respective pusher cylinder. Pressure on each pusher cylinder (40 and 42) is directly related to total frictional components of each respective pusher assembly. Since frictional components of each pusher assembly are unknown factors at any and all times, rack and pinion gear mesh accepts differential loading and distributes it through pinion to racks thus allowing cylinders to maintain synchronization. This mechanical linkage allows both pusher cylinders (40 and 42) to extend at same rate and augments balanced hydraulic fluid flow into them.

In case of one directional valve failure (bad signal, bad wiring, failed PLC output module, etc.) piping geometry merges and then divides flow from remaining directional valve thus keeping balance on each respective pusher cylinder. The system relies on rack and pinion to distribute the load evenly and push will be at slower rate.

In case of failure of rack and pinion assembly an analog position transducer mounted within each pusher cylinder faults the system. This is accomplished by sending a 4-20 Ma signal scaled to the actual position of each respective pusher cylinder to the PLC to be compared to each other. These signals are put into separate registers. These registers are then mathematically compared. A range is set such that 0.375″ difference in pusher cylinder position relative to the other pusher cylinder, faults the system, shuts down push sequence and alarms operator of fault.

In case of a pusher cylinder failure gear rack and pinion will distribute load to allow pusher cylinders to extend together providing failure of cylinder does not starve hydraulic supply to a point where sufficient force cannot be generated to make a push. If force on respective pusher cylinders exceeds the force to keep gear rack meshed, clearances in assembly will allow pusher cylinders to exceed the range for position fault and thus shut down as stated before. In the event that force cannot be developed to push ingot, a PLC timer will time out for maximum push time and fault the system.

Thus electrical signals start ingot pusher sequence by energizing solenoid operated direction valves, energizing hydraulic pump load valves to initiate hydraulic flow, monitor position (movement) of both pusher assemblies to each other for fault monitoring and time complete push cycle for fault monitoring.

Having described the presently preferred embodiments, it is to be understood that the invention may be otherwise embodied within the scope of the appended claims. 

1. A method of upending and indexing rectangular-shaped aluminum ingots on their side through a tunnel furnace, the method comprising the steps of: (a) providing an aluminum rectangular-shaped ingot having two large flat surfaces and two relatively small sides, the ingot provided with said flat surfaces substantially parallel to ground surfaces; (b) providing an apparatus for upending said ingot onto one of said sides, said apparatus comprising: (i) an ingot support frame comprising spaced-apart ingot support members fastened to an axle mounted on a mainframe, said axle rotatable to transfer said ingot from a horizontal to a vertical position to rest on ingot support shoes, said axle having an arm fastened thereto, said arm activated by a first hydraulic means to rotate said ingot support frame; and (ii) a main frame having said ingot support shoes for carrying said ingot on one of said small sides to said tunnel furnace, said shoes traveling on rails passing through said furnace, and having a second hydraulic means in communication with said support shoes to move said ingot into said furnace, thereby horizontally stacking said ingot in said furnace and indexing ingot through said furnace without skewing; (c) placing said flat side of said ingot on said ingot support members; (d) activating said first hydraulic means to position said ingot on said small side on said ingot shoes; and (e) activating said second hydraulic means to move said shoes carrying said ingot into said tunnel furnace and indexing said ingots through said furnace.
 2. The method in accordance with claim 1 wherein said first hydraulic means comprises two hydraulic members connected to arm members disposed on each end of said axle.
 3. The method in accordance with claim 1 wherein said ingot support shoes comprise two shoes and said second hydraulic means comprises two hydraulic members, each hydraulic member in communication with an ingot support shoe for moving said ingot into and through said tunnel furnace.
 4. The method in accordance with claim 3 including providing rack and pinion gears, each gear fastened to said second hydraulic member to prevent said ingot support shoes from skewing in said tunnel furnace.
 5. An apparatus for upending and indexing rectangular-shaped ingot horizontally stack on their side through a tunnel furnace, the ingot having two large flat surfaces and two relatively small sides, the apparatus comprised of: (a) an ingot support frame for receiving an ingot on one of its large flat surface, the support frame having: (i) spaced-apart ingot support members fastened to an axle; and (ii) bearings and bearing supports mounted on a main frame for carrying said axle, said ingot support frame rotatable to transfer said ingot to vertical position having a small side of said ingot resting on ingot support shoes; (b) an arm member having one end fastened to said axle and a second end fastened to a first hydraulic means, said first hydraulic means capable of being activated to rotate said ingot support frame thereby transferring said ingot to said vertical position; (c) a main frame having said ingot support shoes for carrying said ingot on one of said small sides to said tunnel furnace, said shoes mounted rails entering said furnace; and (d) second hydraulic means in communication with said support shoes said second hydraulic means adapted to move said ingot into said furnace.
 6. The apparatus in accordance with claim 5 wherein said first hydraulic means comprises two hydraulic members connected to arm members disposed on each end of said axle.
 7. The apparatus in accordance with claim 5 wherein said ingot support shoes consists of two shoes and said second hydraulic means comprises two hydraulic members, each hydraulic member in communication with each of said shoes for moving said ingots into and through said tunnel furnace.
 8. The apparatus in accordance with claim 7 which includes rack and pinion gears, said gears fastened to said second hydraulic members to prevent said shoes from skewing in said tunnel furnace.
 9. An apparatus for upending and moving rectangular ingot horizontally stack through a tunnel furnace, the ingot having two large flat surfaces and two relatively small sides, the apparatus comprised of: (a) an ingot support frame for receiving and supporting an ingot on one of its large flat surfaces; (i) the support frame having spaced-apart ingot support members fastened to an axle, the support members having a top surface disposed generally horizontally for carrying said ingot on its flat surface, the support member having protrusions extending upwardly for contacting a small side of the ingot; and (ii) bearing support members disposed at each end of said axle, said bearing support members mounted on a main frame, said ingot support frame rotatable to transfer said ingot from a flat surface horizontal position to flat surface vertical position having one of said small sides resting on ingot support shoes; (b) an arm member having one end fastened to said axle and a second end rotatably fastened to a first hydraulic means, said first hydraulic means adapted for rotating said ingot support frame to transfer said ingot to said vertical position; (c) ingot support shoes for carrying said ingot on said small side through said tunnel furnace; (d) a main frame for supporting said support frame; and (e) a second hydraulic means in communication with said support shoes, said second hydraulic means adapted for moving said ingots into and through said furnace.
 10. The apparatus in accordance with claim 9 wherein said first hydraulic means comprises two hydraulic members connected to arm members disposed on each end of said axle.
 11. The apparatus in accordance with claim 9 wherein said ingot support shoes consists of two shoes and second hydraulic means comprises two hydraulic members, each hydraulic member in communication with each of said shoes for moving said ingots into and through said tunnel furnace.
 12. The apparatus in accordance with claim 11 includes rack and pinion gears, said gears fastened to said second hydraulic members to prevent said shoes from skewing in said tunnel furnace. 